Mechanism for operating three-position railway signals



Mach 1'], 1931.

W. J. UNDERWOOD I IECHANISX FOR OPERATING THREE-POSITION RAILWAY SIGNALS Filed llay 20, 1927 4 Slieets-Sheet l V. INVEN'I'OR QL MYZQ ATTORNEYT March 17, 1931. w, UNDERWQQD 1,796,674

MECHANISM FOR OPERATING THREE-POSITION RAILWAY SIGNALS Filed May 20, 1927 4 Sheets-Sheet 2 INVENTOQ March l'l, 1931. w J UNDERWQQD 1,796,674

MECHANISM FOR OPERATING THREE-POSITION RAILWAY SIGNALS Filed May 20, 1927 4 Sheets-Sheet 4 INVENTOR.

By, 2 I

A/TTORNEY.

Patented Mar. 17, 1931 airs s 'r 'ras WALTER JOHN UNDERXVOOIJ, OF CHELSEA, LONDON, ENG-LAND MECHANISM FOR cruel arrive REEE-PGSITIOIJI RAILVIAY SIGNALS Application filed May "20, 192-7, Serial No. 192,831, and in Great Britain December 22, 1926.

This invention relates to fluid pressure 0peratedmechanism tor actuating three-posi tion railway signals, especially signals of the upper quadrant semaphore type.

The mechanism of this kind heretofore proposed has not been generally adopted in practice, and three-position upper quadrant semaphore signals are now usually operated entirely electrically, generally by an induction motor. While this kind or motor mechanislnhas been developed to a high degree of excellence and is very successful in operation, the apparatus is costly and comprises a number or co-operating parts each requiring considerable skill in its design and manufacture. All of these parts, torelrample, the induction slot rotor and stator, the gear train between the motor shaft and the spectacle shaft, the circuit breaker and its special op erating gears, the universal coupling andthe pole changer, must accompany the induction motor for each signalla'nd be accommodated within the housing of the same. In addition a special three-position relay, a product of highly skilled designing and prolonged experiments, must be provided for governing each signal-operating circuit, whilenumerous other auxiliary parts are also required in connection with the electrical distribution system for supplying the alternating current track and signal circuits, such as track transformers, impedance bonds, and the boxes and the like for housing the same alongside or or upon the track, all or which in a lengthy track system represent a very considerable item in the expense of installing andmaintaining the present signalling system employing all-electric three-position signals.

The object of the present inventionis to provide improved fluid pressure operated motor mechanism for three-position signals so that the present all-electric mechanism can be replaced by simpler mechanism of fewer parts requiring considerably reduced initial and maintenance expenditure, and more appropriate for main line working.

Constructional examples offiuid pressure operated motor mechanism for three-position 0 signals according to the invention are illus' trated in the accompanying drawings, in which Fig. l is an elevation partly sectional of an arrangement oi? two compressed air cylinders andpistcns therein for operating a three position signal, the parts being in the danger position Fig. 2 is an elevation of the signal in the corresponding position ona signal post;

8 is an elevationot the arrangement shown in F 1 with the parts in the caution position Fig. i is an elevation of the signal in the corresponding position on a signal post;

Fig. 5 is an elevation of the arrangen'ient shown in Fig. 1 with the parts in the clear position; i

Fig. (3 isan elevation of the signal in the corresponding position on a signal post;

F ig. 7 is an elevation of a modification of the arrangemel'it shown in Figs. 1 and 2, that is, with the parts in the danger position;

F 8 is an elevation of the arrangement shown in Fig. 7 with the parts in the caution position; j

Fig. 9 is an elevation of the arrangement shown in Fig. 7 with the parts in the clear position;

Fi 10 is an elevation of another arrange ment ottwo compressed air cylinders and pistons therein for operating a three-position signal in accordance with the invention, the parts being in the danger position;

Fig. 11 is an elevation of the arrangement shown in Fig. 10 with the parts in the caution position; i

Fig. 12 is an elevation of the arrangement shown in Fig. 10 with the parts in the clear position;

Figs. 13 to 18 illustrate details of alternative means for ensuring the correct order in which compressed air is supplied to and exhausted from the cylinders in the arrangements according to Figs. 10 to 12;

Figs. 19 and 20 are diagrams of electric circuits showing how three-position signals operated according to the invention can suitablybe connected in an automatic signalling system. i

As the invention is essentially of a mechanmotor mechanism are ical nature, consisting of a number of correlated parts the correct operation of which depends largely upon their relative dimensions and locations, the principal dimensions and angles visualized in the design will be given. It will however be understood that these numerical data are in no Way restrictive but are only given as intelligibleexamples; also that the adoption in practice of a different dimension or location for a main part naturally involves different dimensions and locations from those herein given for various other parts dependent upon said main part. In Figures 1 to 12 essential parts of the drawn roughly to a scale of while Figures 13 to 18 are drawn to a scale of The semaphore signal and spectacle are shownslightly in front of the signal post,

that is, on the side facing the observer, while the motor mechanism is entirely on the opposite side. The danger position of the signal is shown as horizontal, the caution position exactly. 45 therefrom in the upper quadrant, and the clear position exactly 90 from the horizontal, also in the upper quadrant.

/ Referring first to Figs. 1 to 6 of the drawing's, the motor mechanism comprises two tically upwards when the cylinder is supplied of a crank shaft 9. The crank arm 8 is of a length of with compressed air. This cylinder may be of theusual standard kind and size used with two-position signals. The piston rod 5 is provided at itsupper-end with a pusher plate 6 adapted to engage a roller 7 on the free end arm 8 fixed upon the spectacle 6 from the axis of the spectacle shaft to that ,of the roller 7 and is inclined downwards at an angle of 22? below the horizontal. l/Vith these dimensions and a roller 7 having a diameter of about 2" the piston 4 makes a stroke of about 5" in the cylinder lin'moving the signal 10 through an angle of 45 into the caution position shown in Figs.

-' 8 and l. The crank arm 8 is curved in the manner shown in order to clear the edge of the pusher plate 6 in the caution position.

A second crank arm 11 is fixed upon the spectacle shaft 9, this arm also being ,Of a ength 0f between centr s and arranged at an angle of 22% to the right ofthe vertical plane through the axis of the shaft 9, in the danger position shown in Figs. 1 and 2, the crank arm 11 being in rear of the crank arm 8.

The second cylinder 2 is provided with trunnions and mounted so as to oscillate thereon about the air admission nozzle 12 and is arranged above the horizontal plane pass ing through the axis of the shaft 9 so that the piston 13 in said cylinder operates clownwards when compressed air isadmitted to the cylinder behind the piston. The cylinder 2 is somewhat longer than the fixed cylinder 1 and its primary function is to move the signal from the caution to the clear position; a

secondary function of this cylinder is to control the movement of the signal from the clear and caution positions to the danger position. In the example shown the cylinder 2 has an overall length of 12" including the a rear end cap and the flanged part of the front cap. The external diameter of the body of the cylinder 2 is shown as 6 and the diameter of the piston13 as 5", but it is probable that smaller dimensions than these would sulfice. The outer end of the piston rod 14; is provided with a fork 15 which is keyed to the free end of the crank arm 11. The axis of the air nozzle 12 andtrunnions of the cylinder 2 is arranged above the horizontal plane passing through the axis of the shaft 9, and

5. to the right (as seenin the figures) of the.

vertical plane passing through said axis.

Compressed air is supplied to the cylinders land 2 by a pipe 16 arranged in any convenient manner on the signal post, from which pipe two branches 17 and 18 are led to the inlets of cylinder 1 and cylinder 2 respectively, the supply and exhaust through branch pipe 17 being controlled by an electromagnetic valve 19 and the supply and exhaust through branch pipe 18 by an elec tromagnetic valve 20. These parts are shown diagrammatically, the pipes in dotted lines, and may be of the kind usually employed with electropneumatic two-position signals. When connected in an automatic signalling system both of the valves 19, 20 for a signal protecting a track section would be de energized on a train entering the section, thus connecting both of the cylinders to the atmosphere and bringing the parts into the positions shown in Figs. 1 and 2, corresponding to the danger position of the signal.

The cylinder 2 is in an inoperative position in Fig. 1, to which it is moved and in which it is held by the Weight of the semaphore and spectacle on returning from the caution or clear position. By the same return movement the piston 18 is forced into the cylinder 2 to a position in which the piston covers and closes the admission opening of the air nozzle 12, while the air trapped between the rear end of the cylinder and the piston cushionsthe finalpartof the descending movement of the signal. This feature is of great importance asit ensures in a very simple manner that the two cylinders acting upon one signal can only be operated in the intended order. To illustrate this action we will suppose that the valve 20 is energized before the valve 19, thatis, in the opposite order to what is intended, owing to an accidental closing of the circuit of said valve 20. In this case although the valve admits the pressure of the air main 16 to the nozzle 12 yet no air can enter the cylinder 2 because theppiston 13 closesthe admission opening. ven it a substantial quantity of air under pressure did penetrate to theupper side of the piston 13 still no movement could be effected because the piston rod 14 and crank arm 11 are nearly end on to one another. Thusthe arrangement oilers a double security against the wrong ord r of operation of thecylinders 1 and 2-, and without requiring any additional part for this purpose. The normal operation is as follows: lVhen a train has completely cleared the track sec tion protected by the signal the electromagnetic valve 19 is energized and admits air under pressure to the fixed or caution cylinder 1, thus raising the piston l therein which engages the roller 7 and rotates the crank arms and shaft 9 through thus also raising the signal 10 through 15 to the caution position, as shown in Figs. 3 and 4. The rotation of the shaft 9 also moves the crank arm 11 clockwise through 45 to a position 22 from the horizontal plane containing the axis of shaft 9, and this movement of crank arm 11 swings the clear cylinder 2 on its trunnions into a position in which the 2118 of the cylinder is vertically over the outer end of the crank arm 11 and at the same time moves the piston 13 about 3 forward in said cylinder, thus uncovering the air admission opening of the nozzle 12 behind the piston, as clearly seen in Figs. 3 and at. v i hen the train .has completely cleared the next section in advance of that protected by signal 10the electromagnetic valve is aergized and admits compressed airto the i r 2 tirough the nozzle 12 thus torcing the piston 13 downwards about 5", rotating the crank arm 11 and shaft 9 through anotherlfi", and bringing the signal 10 into the vertical or clear position shown in Figs. 5 and 6. This movement carries the crank arm 8 and its roller 7 away from the pusher plate 6 into the position sh own, but the cylinder 1 can remain charged and its piston in the uppermost position until the valve 19 is again de-energized.

On a following tram entermg thesection protected by the signal 10 both valves 19 and 20 are de-energized and connect their respective cylinders to atmosphere, thus allowing. the slgnal and. spectacle to descend through 90 into the danger position shown in Figs. 1 and 2 entirely under the control of the cylinder 2, as already stated above.

tromthe clear to the danger position, without stopping at the caution position, and can make that movement under the control 01" the cylinder 2 alone. It will be evident that to obtain the same kind of operation as that described above it is not cz-asential that the cyl inders 1 and 2 should always be arranged. as illustrated in Figs. 1 to 6. It might be possible, for example, to obtain a more compact motor unit by arranging the two cylinders nearer to one another and so as to be quite clear ot the side of the post occupied by the signal lamp.

An arrangement of this kind is illustrated in F 7, 3, and 9, in which the parts are exactly the same and of the same dimensions in Figs. 1 to 6, but the fixed cylinder 1 is arranged uppermost and at the back oi the signal post with its piston operating downwards, while the oscillating cylinder 2 is arranged so that when in the operating position its axis is horizontal, the left side of the signal post 3 occupied by the signal and lamp being entirely free of the motor mechanism.

The two crank arms 8 and 11 are arranged at apart, the crank arm 8 being inclined at 22% above the horizontal in the danger position. The separate parts are indicated by the same reference numerals which they have in Figs. 1 to 6, and the operation is sul stantially the same as that already described with reference to said figures, except that in this case on the cylinder 1 being exhausted of air the action of gravity causes the piston 4L and piston rod 5 to remain in their forward or operative position, so that cylinder 1 cooperates wlth cylinder 2 1n controlling the movement of the s1 gnal from the clear to the danger position.

Referring now to Figs. 10, 11 and 12, the

which in the danger position is inclined downwards at 15 to the horizontal. In this arrangement however the cylinders are not provided with trunnions but each is arranged to oscillate on a hollow lug provided on the rear cap or cover of thecylinder, as shown FL at 23 and 24 respectively, each of the hollow lugs communicating by'a channel with. the space at the back of the piston. This enables the full length of each cylinder to be traversed by the piston in making the power stroke, the length of which is from 8 to 9"; In the arrangement illustrated the caution cylinder 21 is mounted 4 to the right of the vertical plane passing through the axis of the shaft and about 25 below the horizontal plane passing through said axis, while the clear cylinder 22 is mounted 13 to the l ft of said vertical plane and below said horizontal plane. Thus the vertical planes through the axes of oscillation of the two cyinders are 17 apart and the axis of'oscillation of the clear cylinder 22 is 5 higher than that of the caution cylinder 21. The two cylinders are, as before, arranged in rear of the signal post and the signal 10 slightly to the front of the post, while the vertical plane containing the two axes of the cylinders is parallel to the vertical plane in which the signal 10 moves when the shaft 9 is rotated.

The upper end of the piston rod 25 of the caution cylinder 21 terminates in a fork 26 and the upper end of the piston rod 27 of the clear cylinder 22 terminates in a fork 28, and these two forks 26 and 28 are connected by a bar 29 which is 18 in length for the case illustrated. ln the middle part of the bar a bulge or enlargement is provided which is pierced with a round hole to receive a pin 30 pivotally connecting the centre of the bar to the free end of the crank arm 11. The branch pipes 17 and 18 controlled respectively by the electromagnetic valves 19 and 20 are arranged as before to supply air to and exhaust it from the air nozzles and cylinders swinging thereon.

l ith this arrangement of the mechanism however it is necessary to provide means for ensuring that the cylinders are operated only in the correct order, namely, first the cylinder 21 and afterwards the cylinder 22 in raising the signal from the danger to the clear position, and in the opposite order in allowing the signal to return to the danger posit tion, otherwise an accidental operation of the wrong cylinder first might strain the connections. Means for this purpose may act upon r ob the electric circuits of the valves 19 and 20, or may act entirely mechanically upon the air supply to the cylinders without 1n any way affecting the electric circuits. Means of slides a contact piece 33 pivotally connected by a rod 34 to the pin 30 connecting the free end of the crank arm 11 to the bar 29. In the path of the contact piece 33 two contact strips 35, 36 are arranged between and parallel to the guides 31, 32, in such a position that the contact piece 33 only connects the strips 35, 36 when the crank arm 11 is raised to the caution position of the signal. The contact strip is connected by a wire 37 to the exit end of the winding of the electromagnetic valve 20, and the contact strip 36 is connected by a wire 38 to the return lead 39 of the electric supply system for the valves 19, 20, the outgoing leads to which are shown at 40 and 41 respectively. 7

A battery 42 or other additional source of current is provided at each signal and its positive pole is connected to the entry of the winding of the valve 19 while its negative pole is connected to an additional contact strip 43 parallel to but insulated from the strips '35, 36, the strip 43 being of such a length and so disposed that the contact piece 33 only connects it to strip 36 when the signal is moved beyon d the caution towards the clear position.

The operation of the arrangement shown in Figs. 10 to 12 is as follows: In the danger position of the signal (Fig. 10) the circuit of the electromagnetic valve 20 is open at the contact strips 35, 36. lVhen the signal is con trolled automatically by the trains the said circuit is also open at the contacts of the relay connected in the track circuit when a train is on the section protected by the signal. When thetrain leaves the section and the track relay closes its contacts only the valve 19 ought to be at once energized, the circuit of the valve 20 being normally still retained open by a controlling switch dependent upon the condition of the next section in advance, as shown in Figs. 19 and 20, shortly to be described. Valve 19 then admits compressed air to cylinder 21, the piston of which rises and lifts the right hand end of the bar 29, thus rotating crank arm 11 through 45, swinging both cylinders on their pivots slightly to the left, and raising the signal 10 to the caution position as shown in Fig. 11. At the same time the contact piece 33 is raised by the rod 34 to a position in which it connects the strips 35, 36 and thus closes this part of the circuit of the electromagnetic valve 20. Thus, with the parts in the danger position this arrangement makes it impossible for the clear cylinder to be operated before, or even simultaneously with, the caution cylinder, even if the control from the next section in advance should fail to operate correctly.

When the circuit of the electromagnetic valve 20 is also closed at the contacts of the relay controlling that circuit the valve is energized and admits compressed air to cylinder 22,:cylinder 21 also remaining charged and its piston fully raised. The piston in cylinder 22- therefore rises-and lifts the lefthand end of the bar 29, thus rotating the crank arm 11 throughafurther45, swinging both cylinders slightly to the right on their pivots, and raising the signal into the vertica-l or clear position, as shown in 12.

Throughout this movement the strips 35, 36

remain connect-ed by the contact piece 33 i which also closes the circuit of the battery 42 21, when the signal is returned from the clear to the danger position. WVith the parts as shown in Fig. 12, when a train enters the section protected by the signal 10 the relay controlling the signal is de-energized and opens the circuits of both of the valves 19 and 20.

As however the circuit of the valve 19 is closed through the battery 42 this valve remains energized; hence only the cylinder 22 is exhausted at first, but when its piston has descended to a suflicient extent to cause the contact piece 33 to leave the strip 43 and the signal is approaching the caution position (Fig. 11) then the circuit from the battery 42 through valve 19 is opened and this valve also is deenergized, thus exhausting cylinder 21 and allowing its piston to descend and the signal to continue its downward movement to the danger position (Fig. 10).

The same result can be obtained by a valve device acting directly upon the air supply as shown in Figs. 13 to 18, and without in any way interfering with the electric circuits of the valves 19 and 20. In this case the rod 34 is connected to a lever 44 arranged to rotate the rotary part 45 of a plug valve having a casing 46 which is fixed to the signal post by means of a base plate 47, the lever 44 occupying a position parallel to the crank arm 11 in the various positions of the signal. Fig. 13

shows the plug valve in operative position with its small end towards the rear and the branch pipe 17 connected to one of a pair of nipples 48 on the right side of the casing 46, a pipe 1'? connecting the other nipple of the pair to the inlet of cylinder 21, the branch pipe 18 connected to one of another pair of nipples 49 on the left, and a pipe 18 connecting the other nipple of this pair to inlet of cylinder 22. Fig. 14 shows the rotary part 45 and lever 44 separately; the former is adjusted in operative position in the case 46 by 'means of a nut 50 working on the screwed spindle of the rotary part, while the lever is pinned upon the square outer end of said spindle. Fig. 15 is a view of one side of the valve casing showing the nipples 48; Figs. 16, 17 and 18 show the positions of the lever 44 corresponding respectively to the danger, caution, and clear positions of the signal, these figures being sections on the line 2555 of F ig. 15. Recesses 51, 52 are formed in the rotary part 45 and so arranged that in the danger position shown in Fig. 16 the recess 51 connectsthe nipples and allows cornpressed air to llow between them, while the recess 52 fails to connect the nipples 1-9, the passage between which therefore shut ell", sothat no air can-be supplied to the clear cylinder 22 even if its valve 20 shouldbe accidentally energized. In the caution position shownin Fig. 17 therecess in the rotary plug 45' connects-the nipples 49 and the recess 51 continues to connect the nipples 48, so that the air supply to both cylinders open. In the clearposition shown in Fig. 18 the-nipples 49 remain connected by the recess 52 butthe recess 51 has now moved completely away from the nipples 48, the passage throughwhich is therefore shut off thus preventing the air escaping from cylinder 21 untilthepiston in cylinder22 has descended nearly tothe caution position. The air can then esca so from cylinder 21 and its piston therefore descends bringingtheparts a ain to the position. shown in F ig. 16. Figs19 and 20 show diagrammatically the usual elements of automatic signalling systems employing two-position signals, with modified connections according to the invention to adapt the systeinto the use of thrc position signals operated by the motor mechanism hereinabove described. 'lhree track sections I, II, III, are shown with corresponding signals X X X respectively, a train being shown on section III travelling from right to left. The uppermost of the two valves shown at each signal in each figure corresponds to valve 19 and controls the caution cylinder, while the lower valve correspoinls to valve 20 and controls the clear cylinder for each signal, but only the valves and their cir cuits are shown, the latter being fed from direct current signalling mains 53, 54 extending along the track and maintained at a suitable voltage. Track relays A A A of any ordinary kind areprovided corresponding to thesections I, II, III respectively and each relay has two armaturosB B of whichB controls the circuit ofthe valve 19 and 15;; that of the valve 20 for the corresponding signal: y

In Fig. 19 the circuit of each valve 20 is alsocontrolled by a switch S operated by the signal X of the section in advance, the switch being open when the signal is in the danger position and closed when the signal is in the cautionand clear positions. In Fig. 20 the signal switches S are dispensed with, and each valve 20 is controlled both by the armatu-re of the corresponding relay A and alsobythe armature B of the relay corresponding to the signal in advance.

gized and both of-its armatures B B are raised. Consequently signal X cannot be raised beyond the caution position shown. As the switch S is closed in this position both valves 19 and 20 of the signal X in rear are energized and consequently this signal is in the clear position indicating to a following train that both sections I and II are unoccupied by a train. tures B of each relay A is used, instead of the signal-operated switch S, to control both 1 the circuit of the corresponding caution valve 19 and also the circuit of the clear valve 20 of the signal in rear. This gives the same eifect as the arrangement shown in Fig. 19, but enables the switches S to be dispensed with, as will readily be seen from the diaram. 7 I

What I claim and desire to secure by Letters Patent is 1'. Fluid pressure operated motor mechanism for theactuation of a three-position railway signahcomprising a caution cylinder, an oscillating clear cylinder, a piston sliding in each cylinder, means for supplying fluid under pressure to the two cylinders, and connections from the two pistons to the signal for moving the signal successively from the danger to the caution position and from the caution to the clear position.

2. Motor mechanism according to claim 1, comprising a nozzle for admittlng compressed air to the clear cylinder coaxial with the ax1s of oscillatlon, and connections for the piston to the signal shaft such that in the danger'position of the signal the piston in the oscillating cylinder closes the opening or" the In Fig, 20 the arrnamoving the said cylinder round its axis of v oscillation into an inoperative position by the movement of the signal from the caution to the danger position and for moving said cylinder into an operative position by the reverse movement of the signal from the danger to the caution position. I

3. Motor mechanism according to claim 1, comprising a crank arm on the signal shaft for engagement by the piston rod of the caution cylinder, an anti-friction roller mounted on the end of the crank arm, and a pusher plate on the end of said piston rod adapted to engage the said anti-friction roller and to allow movement of the crank arm without der, a nozzle for admittingcompressed air to the cylinder co-axial with the axisfof oscillation of the cylinder, and a connection from 

